1. Field of the Invention
The present invention relates to fire extinguishing sprinklers adapted to respond quickly to the presence of heat exceeding a predetermined temperature, which can be mounted substantially flush with the ceiling of a fire protected enclosure.
2. Description of the Prior Art
Quick response sprinkler systems are a commonly used means for automatically protecting residential, commercial and public buildings from a fire. It has been generally recognized in the fire protection industry that one goal of quick response sprinkler devices is to minimize the unsightly appearance of the sprinkler. Attempts to minimize the unsightliness of sprinkler devices include installing sprinklers in an enclosure which is mounted flush with the ceiling or wall of the fire protected room. However, such enclosures create thermal insulation, whereby the temperature response mechanism of the sprinkler device is somewhat insulated from the fire protected room, thereby reducing thermal response time for sprinkler activation. It is often desirable, therefore, to expose the temperature responsive portion of the sprinkler device to the ambient conditions of the room or building to be protected by the sprinkler device.
Other attempts to minimize the unsightliness of sprinkler devices include reducing the size and portion of the sprinkler device which extends into a fire protected room. For example, in several conventional sprinklers, the temperature responsive portion of the sprinkler is extended into the room or building enclosure only as much as is necessary to place a temperature responsive mechanism into direct or nearly direct air contact with the fire protected room, leaving the remainder of the sprinkler (the body and the valve and locking mechanisms) generally out of sight.
One example of such a device is disclosed by U.S. Pat. No. 4,465,141, which discloses a fire sprinkler having a locking and latching mechanism internally disposed in a sprinkler body and a temperature responsive mechanism extending outwardly from the sprinkler body and into a fire protected room when installed. The sprinkler disclosed by this patent has a slideable valve and deflector arrangement which is held in retracted condition by a complex captive locking mechanism which moves with the valve from the closed to the opened position and both the valve and locking mechanisms are retained by the sprinkler body. However, the combined valve, locking and latching mechanism, being retained by the sprinkler assembly during operation, obstructs the flow of fluid from the sprinkler and results in a decreased fluid distribution pattern from the sprinkler. In addition, this combined mechanism is relatively expensive to manufacture, requiring a high tolerance assembly and relatively large amounts of anti-corrosive materials forming the combined valve, locking and latching mechanism.
Recognizing the difficulties and inefficiencies inherent in the device disclosed by U.S. Pat. No. 4,465,141, U.S. Pat. No. 4,766,961 discloses a fire sprinkler apparatus wherein the valve is separate and distinct from the locking mechanism. However, during actuation of the sprinkler apparatus disclosed in this patent, the locking mechanism, including the thermally responsive mechanism, is ejected from the sprinkler body under the force of the fire extinguishing fluid and ejector springs mounted on the sprinkler body. The valve is retained by the sprinkler body.
Unlike the apparatus disclosed in U.S. Pat. No. 4,465,141, the locking mechanism of the sprinkler disclosed in the latter patent is external to the sprinkler body and relatively large. When actuated, the larger locking mechanism is propelled from the sprinkler (often under forces of 50 to 200 psi), becoming a source of danger for persons or materials in the vicinity of the actuated sprinkler. Moreover, because the locking mechanism is external to the sprinkler body, the locking mechanism and thermally responsive mechanism protrude further into a fire protected room than do the corresponding mechanisms disclosed in, for example, U.S. Pat. No. 4,465,141. Thus, the device disclosed in this patent is unsightly and dangerous.
In the view of the deficiencies and inefficiencies of the prior art, it would be desirable to have a fire sprinkler apparatus which has a good fluid distribution pattern, which is relatively simple and inexpensive to produce, which is visually appealing when installed and which exhibits a safe, quick response to a predetermined elevated temperature.